1. Field of the Invention
The present invention relates to a device for producing various data relating to camera accessories, such as interchangeable lenses, lens adaptors, and so on. More particularly, it relates to a device in which a fixed memory device stored with various data, such as a type of accessory, an aperture size, a focal length, and the like, is installed in a camera accessory, and such data are read out, when the camera accessory is attached to a camera body, in the camera.
2. Description of the Prior Art
It is known in the prior art, such as disclosed in Japanese Laid-Open Patent Application No. 54-108628, to provide a ROM (read-only-memory) in each camera accessory, such as in each interchangeable lens, to store various data, for example aperture size and focal length. When the lens is connected to the camera body, the ROM's address is sequentially specified to supply various data stored in ROM to the camera. According to this prior art, however, a ROM memorizes data only related to the accessory in which that ROM is employed and, therefore, for the different accessories it is necessary to provide ROMs stored with different data. Generally, the manufacturing cost of ROMs and its associated circuits (usually formed by an integrated circuit) is inversely proportional to the amount of manufactured pieces and, therefore, the lesser the number of ROMs to be manufactured, the higher the manufacturing cost for each ROM. Since the special use accessories, such as super telephoto lens and super wide-angle lens, are manufactured at a relatively low number, the ROMs and associated ICs to be installed in such special use accessories are very few in number Therefore, the manufacturing cost of such ROMs and ICs become very high, resulting in extra-high cost in manufacturing special use accessories. As apparent from the above, the prior art device has a disadvantage in creating a high manufacturing cost of data carrying camera accessories, particularly those manufactured at a low number.